The risk to heart health appears to be strongest in the first year after diagnosis of migraine, but persists for as long as two decades, said lead researcher Dr. Kasper Adelborg. He is a postdoctoral fellow of clinical epidemiology at the Aarhus University Hospital in Denmark.

“Accumulating evidence supports that migraine should be considered as an important risk factor for most cardiovascular diseases in both men and women,” Adelborg said.

Migraine affects about 15 percent of people, mainly women, and was the second leading cause of years lost to disability in 2016, according to background information provided by the researchers.

For the study, Adelborg and his colleagues gathered records from patients treated at Danish hospitals and hospital outpatient clinics between 1995 and 2013. The investigators wound up with just over 51,000 migraine patients and slightly more than 510,300 non-migraine patients matched for comparison.

The findings showed that migraine patients more frequently suffered a host of heart- and blood vessel-related health problems, though a cause-and-effect relationship wasn’t proven.

27 migraine patients developed life-threatening blood clots in their veins, compared with 18 people without migraines.

47 people with migraine developed an irregular heartbeat, versus 34 migraine-free people.

Migraine remained linked to these heart problems even after researchers took into account other risk factors, such as excess weight or smoking.

The findings were published online Jan. 31 in the BMJ.

In an editorial that accompanied the study, Dr. Tobias Kurth, an adjunct professor of epidemiology with the Harvard T.H. Chan School of Public Health, and colleagues wrote: “We now have plenty of evidence that migraine should be taken seriously as a strong cardiovascular risk marker.”

Despite these observations, the absolute risk for all heart-related health problems remained low. That was expected, the researchers noted, given that the patients evaluated in this study were relatively young, with an average age of 35.

That means that an individual’s risk of heart attack or stroke won’t necessarily increase drastically if they suffer migraines.

However, Adelborg said, in the broad scheme of things, the increased risk from migraines must be taken seriously.

“Although the absolute risks of cardiovascular diseases were low at the individual level, it translates into a substantial increase in risk at the population level, because migraine is a very common disease,” he explained.

The researchers cannot say with certainty why migraines might pose a potential threat to heart health, but they have some theories.

For example, cerebral arteries sometimes suddenly constrict during a migraine, which could increase stroke risk, Adelborg said. People suffering from a migraine also often lie down for long periods of time, which can make blood clots more likely.